1、Designation: D 3972 09Standard Test Method forIsotopic Uranium in Water by Radiochemistry1This standard is issued under the fixed designation D 3972; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of alpha-particle-emitting isotopes of uranium in water by means ofchemical separations and alpha
3、 pulse-height analysis (alsoknown as alpha-particle spectrometry). Uranium is chemicallyseparated from a water sample by coprecipitation with ferroushydroxide, anion exchange, and electrodeposition. The testmethod applies to soluble uranium as well as to any uraniumthat might be present in suspended
4、 matter in the water sample.This test method is applicable for uranium processing effluentsas well as substitute ocean water. When suspended matter ispresent, an acid dissolution step is added to assure that all ofthe uranium dissolves. It is the users responsibility to ensurethe validity of this te
5、st method for waters of untested matrices.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of t
6、he user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific warningstatements are given in Section 9.2. Referenced Documents2.1 ASTM Standards:2C 859 Terminology Relating to Nuclear MaterialsC 1163 P
7、ractice for Mounting Actinides for Alpha Spec-trometry Using Neodymium FluorideD 1066 Practice for Sampling SteamD 1129 Terminology Relating to WaterD 1192 Guide for Equipment for Sampling Water andSteam in Closed Conduits3D 1193 Specification for Reagent WaterD 2777 Practice for Determination of Pr
8、ecision and Bias ofApplicable Test Methods of Committee D19 on WaterD 3084 Practice for Alpha-Particle Spectrometry of WaterD 3370 Practices for Sampling Water from Closed ConduitsD 3648 Practices for the Measurement of RadioactivityD 5847 Practice for Writing Quality Control Specificationsfor Stand
9、ard Test Methods for Water AnalysisD 7282 Practice for Set-up, Calibration, and Quality Con-trol of Instruments Used for Radioactivity Measurements3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminologies C 859 and D 1129. For terms not included int
10、hese reference may be made to other published glossaries.4,54. Summary of Test Method4.1 The water sample to be analyzed is acidified and232Uisadded to serve as an isotopic tracer before any additionaloperations are performed. If the sample is a seawater sample,or if it contains carbonate or bicarbo
11、nate ions, the sample mustbe boiled under acidic conditions to convert these ions tocarbon dioxide gas which is then expelled from the solution.Carbonate ions must not be present during the precipitationstep because they complex the uranium and prevent itscoprecipitation. The uranium is coprecipitat
12、ed from the samplewith ferrous hydroxide. This precipitate is dissolved in con-centrated hydrochloric acid, or is subjected to an acid dissolu-tion with concentrated nitric and hydrofluoric acids if thehydrochloric acid fails to dissolve the precipitate.4.2 The uranium is separated from other radion
13、uclides byadsorption on anion-exchange resin from 8 M hydrochloricacid, followed by elution with 0.1 M hydrochloric acid. Theuranium is electrodeposited onto a stainless steel disk. Isotopicuranium radioactivities are measured by alpha pulse-heightanalysis with a silicon surface-barrier or ion-impla
14、nted detectorand a multichannel analyzer.4.3 When232U is used as the tracer, the other isotopes ofuranium listed in Table 1 can be detected in the alpha-particlespectrum of an unknown sample. From the alpha energies1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the
15、direct responsibility of Subcommittee D19.04 on Methods of Radiochemi-cal Analysis.Current edition approved Feb. 1, 2009. Published March 2009. Originallyapproved in 1980. Last previous edition approved in 2002 as D 3972 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcont
16、act ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.4Parker, S. P., ed., Dictionary of Chemica
17、l Terms, McGraw-Hill Book Co.,New York, NY, 1985.5IUPAC, “Glossary of Terms Used in Nuclear Analytical Chemistry,” Pure andApplied Chemistry, Vol 54, 1982, pp. 15331554.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.given in the tab
18、le, it can be seen that the alpha energy of232Uis more than 0.40 MeV higher than the energy of any otheruranium isotope. Thus, there should be little interference fromtailing of the232U into the lower energy alpha peaks.233Uand234U usually cannot be resolved because their principalalpha energies dif
19、fer by only 0.04 MeV.235U and236U peakscan be resolved only with difficulty. The alpha peaks fromother combinations of uranium isotopes can be resolved unlessthe quality of the finally prepared sample is poor.5. Significance and Use5.1 This test method was developed to measure the radio-activity of
20、uranium isotopes in environmental waters or watersreleased to the environment, and to determine whether theuranium-isotope concentrations are below the maximumamounts allowable by any regulatory statute.6. Interferences6.1 Thorium, polonium, plutonium, and americium werefound not to interfere in thi
21、s uranium determination.6The onlypossible alpha-emitting isotopes that might interfere, based onthe chemistry of this test method, are231Pa (3.28 3 104yhalf-life) and237Np (2.16 3 106y half-life). These isotopes,however, are not likely to be present in environmental watersamples. Protactinum-231 has
22、 the following alpha energies inMeV, the abundance being given in parentheses: 5.013(25.4 %), 5.03 (23 %), 4.951 (22.5 %), 5.059 (11 %), and 4.734(8.4 %). Thus, from Table 1, it is seen that231Pa can interferewith the determination of233Uor234U. However, when the4.951 to 5.059 MeV231Pa peaks can be
23、resolved from theuranium peaks, a correction can be made. Neptunium-237 hasalpha emission energies ranging from 4.639 to 4.873 MeV,with 72 % found between 4.771 and 4.788 MeV. Conventionalanalytical equipment would not be able to resolve these peaksfrom normal234U emissions. If Np-237 is suspected t
24、o bepresent in the sample, a separate237Np analysis would berequired to make the appropriate correction to the234U result.6.2 When measuring very low concentrations of uraniumisotopes in environmental samples, detector backgrounds andlaboratory blanks must be well known. Blank determinationsare made
25、 to ascertain that any contamination from reagents,glassware and other laboratory apparatus is small compared tothe activity in the sample that is being analyzed. A blankdetermination should be made in exactly the same way as thesample determination.7. Apparatus7.1 Centrifuge, 250-mL centrifuge bott
26、le or tube capacity.7.2 Ion Exchange Column, glass or plastic, approximately13-mm inside diameter and 150 mm long with a glass-woolplug or plastic frit and a 100- to 150-mL reservoir.7.3 Electrodeposition Apparatus, consisting ofa0to12-V,0 to 2-A power supply (preferably constant current) and anelec
27、trodeposition cell. The cathode is an approximately 20-mmdiameter stainless steel disk polished to a mirror finish. Theanode is approximately 1-mm diameter platinum wire with anapproximately 8-mm diameter loop at the end of the wireparallel to the cathode disk. Cooling of the electrolyte duringelect
28、rodeposition to at least 50C is recommended. See refer-ences in Section 8 of Practice D 3084 for more details.7.4 Alpha Pulse-Height Analysis System, consisting of asilicon surface-barrier or ion-implanted detector, supportingelectronics, and pulse-height analyzer. A system capable ofgiving a resolu
29、tion of 30 keV FWHM or better, when measuredwith a high-quality source, is recommended. The countingefficiency of the system should be greater than 15 %, and thebackground in the energy region of each peak should be lessthan ten counts in 60 000 s.8. Reagents and Materials8.1 Purity of ReagentsReage
30、nt grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society.7Other grades may be used provided it is first ascertained thatthe reagent is of suffi
31、ciently high purity to permit its usewithout reducing the precision, or increasing the bias, of thedetermination.8.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Specifications D 1193, Type III, as a minimum.8.3 Radioactive Purit
32、y of ReagentRadioactive purity shallbe such that the measured results of blank samples do not6Bishop, C. T., Casella, V. R., and Glosby, A. A., “Radiometric Method for theDetermination of Uranium in Water: Single-Laboratory Evaluation and Interlabo-ratory Collaborative Study,” U.S. Environmental Pro
33、tection Agency Report,EPA600/7-79-093, April 1979.7Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poo
34、le, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.TABLE 1 Relevant Properties of Uranium Isotopes of Interest inEnvironmental WatersAIsotopeHalf Life Principal Alpha Energies in MeVYears (Abundance)232U 68.9 5.320(68.
35、6)5.262(31.4)233U 1.592 3 1054.824(83.3)4.782(14.1)234U 2.455 3 1054.774(72.5)4.722(27.5)235U 7.038 3 1084.596(5.6)4.307 (57)4.366 (17)4.214(6.4)236U 2.342 3 1074.493 (74)4.445 (26)238U 4.468 3 1094.198 (77)4.151 (23)ATable of Isotopes, Eighth Edition, Vol. 11, Richard B. Firestone, LawrenceBerkeley
36、 National Laboratory, University of California, 1996.D3972092exceed the calculated probable error of the measurement or arewithin the desired precision.8.4 Ammonium Hydroxide (sp gr 0.90)Concentrated am-monium hydroxide (NH4OH).8.5 Ammonium Hydroxide Solution 0.15 M (1+99)Mix 1volume of concentrated
37、 NH4OH (sp gr 0.90) with 99 volumesof water. This solution is 0.15 M.8.6 Anion-Exchange ResinStrongly basic, styrene, quater-nary ammonium salt, 4 % crosslinked, 100 to 200 mesh,chloride form.8.7 ElectrolyteDissolve 132 g of ammonium sulfate inwater and dilute to 1 L. Slowly add concentrated NH4OH o
38、rconcentrated H2SO4while stirring to adjust the pH of thesolution to 3.5. The solution is 1 M in (NH4)2SO4.8.8 Ethyl Alcohol (C2H5OH)Make slightly basic with afew drops of concentrated NH4OH per 100 mL of alcohol.Anhydrous denatured ethanol is acceptable.8.9 Ferric Chloride Carrier Solution (20 mg F
39、e/mL)Dissolve 9.6 g of FeCl36H2O in 100 mL of 0.5 M HCl.8.10 Filter paper, ashless, medium porosity.8.11 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).8.12 Hydrochloric Acid 8 M (2+1)Mix 2 volumes ofconcentrated HCl (sp gr 1.19) with 1 volume of water. Thissolution is 8 M.8.13
40、Hydrochloric Acid 0.5 M (1+23)Mix 1 volume ofconcentrated HCl (sp gr 1.19) with 23 volumes of water.8.14 Hydrochloric Acid 0.1 M (1+119)Mix 1 volume ofconcentrated HCl (sp gr 1.19) with 99 volumes of water. Thissolution is 0.1 M.8.15 Hydrofluoric Acid (sp gr 1.2)Concentrated hydrof-luoric acid (HF).
41、8.16 Hydroiodic Acid (sp gr 1.5)Concentrated hydroiodicacid (HI).8.17 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).8.18 Sodium Hydrogen SulfateSulfuric AcidDissolve 10g of sodium hydrogen sulfate in 100 mL of water and thencarefully add 100 mLof concentrated H2SO4(sp gr 1.84) whilestirring
42、. This solution contains about5gofNaHSO4per 100mL of 9 M H2SO4.8.19 Sodium Hydrogen Sulfite (NaHSO3).8.20 Sulfuric Acid (sp gr 1.84)Concentrated sulfuric acid(H2SO4).8.21 Sulfuric Acid 1.8 M (1+9)Cautiously add with stir-ring 1 volume of concentrated sulfuric acid (sp gr 1.84) to 9volumes of water.
43、This solution is 1.8 M.8.22 Thymol Blue Indicator SolutionDissolve 0.04 g ofthe sodium salt of thymol blue in 100 mL of water.8.23 Uranium-232 Solution, Standard (about 0.2 Bq/mL).9. Precautions9.1 Hydrofluoric acid (HF) is very hazardous and should beused in a well-ventilated hood. Wear rubber glov
44、es, safetyglasses or goggles, and a laboratory coat. Avoid breathing anyHF fumes. Clean up all spills promptly and wash thoroughlyafter using HF. Ready availability of a topical fluoride bindingagent, such as calcium gluconate gel, is strongly recommendedin the event of skin contact with HF.10. Samp
45、ling10.1 Collect the sample in accordance with PracticesD 1066, D 3370 and Specification D 1192 as applicable. Pre-serve the sample by adjusting the pH to 1 with concentratedHCl if the sample is not to be analyzed within 24 h. Record thevolume of the sample and the volume of acid added.11. Calibrati
46、on and Standardization11.1 Standardized232U is required as a tracer. Before stan-dardization, this isotope must be separated from its radioactivedescendents by anion exchange or some other means ofchemical separation. See Practices D 3084 and D 3648 forgeneral guidance concerning the standardization
47、 of tracers, andthe energy and efficiency calibrations of the detector. Thepulse-height analyzer should be set to accept pulses from alphaparticles of approximately 3.5 to approximately 9.0 MeV inenergy.12. Procedure12.1 Coprecipitation:12.1.1 Measure the volume of approximately 1 L of thewater samp
48、le to be analyzed and transfer to a 2-L beaker.12.1.2 If the sample has not been acidified, add 5 mL ofconcentrated HCl.12.1.3 Add a magnetic stirring bar, mix the sample com-pletely, and check the acidity with pH-indicating paper or strip.If the pH is greater than 1, add concentrated HCl with mixin
49、guntil it reaches this value.12.1.4 Add approximately 0.2 Bq of standardized232Utracer with a calibrated pipet or by weight.12.1.5 If the sample is a seawater or if it may containcarbonate ions, it must be boiled for approximately 5 min.Check the pH again after boiling and if it is greater than 1, addconcentrated HCl with mixing to bring the pH back to 1.12.1.6 Add approximately 500 mg of NaHSO3and2mLofferric chloride carrier solution.12.1.7 Cover the sample with a watch glass and heat thesample to boiling for 10 min.12.1.8 Without removing the watch glass, a
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